Liquid crystal display device

ABSTRACT

A liquid crystal display device with a pair of substrates which are arranged to face each other with liquid crystal therebetween, columnar spacers having the substantially equal height formed on a liquid-crystal-side surface of one substrate, and the columnar spacers include the columnar spacer which is contact with a liquid-crystal-side surface of another substrate and the columnar spacer which is not contact with the liquid-crystal-side surface of another substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

1. Technical Field

This application is a Continuation application of U.S. application Ser.No. 14/718,210, filed May 21, 2015, which is a Continuation of U.S.application Ser. No. 14/229,646 filed Mar. 28, 2014, which is aContinuation application of U.S. application Ser. No. 13/771,801 filedFeb. 20, 2013, which is a Continuation application of U.S. applicationSer. No. 12/926,769 filed Dec. 8, 2010, which is a Continuationapplication of U.S. application Ser. No. 12/458,090 filed Jun. 30, 2009,which is a Continuation application of U.S. application Ser. No.12/149,581 filed May 5, 2008, which is a Continuation application ofU.S. application Ser. No. 10/969,042 filed Oct. 21, 2004. Priority isclaimed based on U.S. application Ser. No. 14/718,210, filed May 21,2015, which claims priority to U.S. application Ser. No. 14/229,646filed Mar. 28, 2014, which claims priority to U.S. application Ser. No.13/771,801 filed Feb. 20, 2013, which claims priority to U.S.application Ser. No. 12/926,769 filed Dec. 8, 2010, which claimspriority to U.S. application Ser. No. 12/458,090 filed Jun. 30, 2009,which claims priority to U.S. application Ser. No. 12/149,581 filed May5, 2008, which claims the priority date of U.S. application Ser. No.10/969,042 filed Oct. 21, 2004, which claims the priority date ofJapanese Application No. 2003-365378 filed on Oct. 27, 2003, and whichis hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, andmore particularly to so-called columnar spacers which are formed forensuring a gap between respective substrates which are arranged to faceeach other in an opposed manner with a liquid crystal therebetween.

2. Description of the Related Art

In the liquid crystal display device, to ensure a gap between respectivesubstrates which are arranged to face each other in an opposed mannerwith liquid crystal therebetween, spacers are interposed between therespective substrates. As such spacers, there have been known spacerswhich are referred to as columnar spacers, for example.

That is, a layer formed of resin, for example, is formed on aliquid-crystal-side surface of one substrate out of the respectivesubstrates, wherein the layer is formed by a selective etching method.Accordingly, this method has an advantage that the necessary number ofcolumnar spacers can be formed at necessary portions between thesubstrates.

However, in the liquid crystal display device having such aconstitution, the friction resistance between the columnar spacers andanother substrate which is brought into contact with the columnarspacers is increased and hence, when another substrate is displaced inthe planar direction with respect to one substrate, there may be a casethat the displacement is not restored and the brightness irregularitiesattributed to the displacement between a pixel region of the uppersubstrate and a pixel region of the lower substrate is generated.

Further, Japanese Unexamined Patent Publication 2003-131238 discloses anexample which includes columnar spacers which differ in height as astate of the columnar spacers in the manufacturing steps.

SUMMARY OF THE INVENTION

However, the liquid crystal display device having such a constitutionhas a drawback that it is necessary to form the respective columnarspacers which differ in height and the irregularities of accuracy ofthese spacers are large.

The present invention has been made in view of such circumstances and itis an advantage of the present invention to provide a liquid crystaldisplay device which is capable of coping with the displacement in thelateral direction and an excessive pressure applied to substrateswithout increasing manufacturing steps, for example.

To briefly explain examples of representative inventions among theinventions disclosed in this specification, they are as follows.

(1) The liquid crystal display device according to the present inventionis, for example, a pair of substrates which are arranged to face eachother with liquid crystal therebetween, columnar spacers having thesubstantially equal height formed on a liquid-crystal-side surface ofone substrate, and the columnar spacers include the columnar spacerwhich is contact with a liquid-crystal-side surface of another substrateand the columnar spacer which is not contact with theliquid-crystal-side surface of another substrate.

(2) The liquid crystal display device according to the present inventionis, for example, a pair of substrates which are arranged to face eachother with liquid crystal therebetween, columnar spacers having thesubstantially equal height formed on a liquid-crystal-side surface ofone substrate, the columnar spacers include the columnar spacer which iscontact with a liquid-crystal-side surface of another substrate and thecolumnar spacer which is not contact with the liquid-crystal-sidesurface of another substrate, and the columnar spacers are arranged suchthat the around the respective columnar spacers which are brought intocontact with the liquid-crystal-side surface of another substrate, thecolumnar spacers which are not brought into contact with theliquid-crystal-side surface of another substrate are arranged.

(3) The liquid crystal display device according to the present inventionis, for example, a pair of substrates which are arranged to face eachother with liquid crystal therebetween, columnar spacers formed on aliquid-crystal-side surface of one substrate, and the columnar spacersinclude first columnar spacer and second columnar spacer, and aliquid-crystal-side surface of another substrate where the firstcolumnar spacer contact has a projecting shape.

(4) The liquid crystal display device according to the present inventionis, for example, a pair of substrates which are arranged to face eachother with liquid crystal therebetween, columnar spacers formed on aliquid-crystal-side surface of one substrate, and the columnar spacersinclude first columnar spacer and second columnar spacer, and portion ofanother substrate which face the first columnar spacer is set higherthan portion of another substrate which face the second columnar spacer.

(5) The liquid crystal display device according to the present inventionis, for example, on the premise of the above-mentioned constitution (3),the projecting shape of the liquid-crystal-side surface of anothersubstrate with which the first columnar spacer contact is formed by amaterial having a thickness interposed as a layer below an insulationfilm.

(6) The liquid crystal display device according to the present inventionis, for example, on the premise of the above-mentioned constitution (4),the portion of another substrate which face the first columnar spacer inan opposed manner is formed by a material having a thickness interposedas a layer below an insulation film.

(7) The liquid crystal display device according to the present inventionis, for example, a pair of substrates which are arranged to face eachother with liquid crystal therebetween, columnar spacers formed on aliquid-crystal-side surface of one substrate, and the columnar spacersinclude first columnar spacer and second columnar spacer, and surfacesof another substrate which face the second columnar spacer have arecessed shape.

(8) The liquid crystal display device according to the present inventionis, for example, on the premise of the above-mentioned constitution (3),the first columnar spacer is arranged such that the second columnarspacers are provided around the first columnar spacer.

(9) The liquid crystal display device according to the present inventionis, for example, on the premise of the above-mentioned constitution (4),the respective first columnar spacer is arranged such that the secondcolumnar spacers are provided around the first columnar spacer.

(10) The liquid crystal display device according to the presentinvention is, for example, a pair of substrates which are arranged toface each other with liquid crystal therebetween, at least a thin filmtransistor formed on one substrate in each pixels and the thin filmtransistor have semiconductor layer, columnar spacers formed on anothersubstrate, and having another semiconductor layer which is spaced apartfrom the semiconductor layer of the thin film transistor in plane view,and the columnar spacers include at least a columnar spacer arranged ina manner to face the another semiconductor layer and at least a columnarspacer arranged in a manner not to face the another semiconductor layer.

(11) The liquid crystal display device according to the presentinvention is, for example, on the premise of the above-mentionedconstitution (10), the another semiconductor layers are formed over gatesignal lines which drive the thin film transistors of the respectivepixels.

(12) The liquid crystal display device according to the presentinvention is, for example, on the premise of the above-mentionedconstitution (10), the respective columnar spacers have thesubstantially equal height.

(13) The liquid crystal display device according to the presentinvention is, for example, on the premise of the above-mentionedconstitution (10), the another semiconductor layers are formed in thesame step as the semiconductor layers of the thin film transistors.

(14) The liquid crystal display device according to the presentinvention is, for example, on the premise of the above-mentionedconstitution (10), another semiconductor layers constitute the samelayers as the semiconductor layers of the thin film transistors.

(15) The liquid crystal display device according to the presentinvention is, for example, on the premise of the above-mentionedconstitution (10), diameter of the columnar spacer arranged in a mannernot to face the another semiconductor layer is greater than a columnarspacer arranged in a manner to face the another semiconductor layer.

(16) The liquid crystal display device according to the presentinvention is, for example, on the premise of the above-mentionedconstitution (4), the difference in height between the portions ofanother substrate which face the first columnar spacers in an opposedmanner and the portions of another substrate which face the secondcolumnar spacers in an opposed manner is equal to or more than 0.06 μmand equal to or less than 0.18 μm.

(17) The liquid crystal display device according to the presentinvention is, for example, on the premise of the above-mentionedconstitution (10), the difference in height between the portions of onesubstrate where another semiconductor layer is formed and the portionsof one substrate where another semiconductor layer is not formed isequal to or more than 0.06 μm and equal to or less than 0.18 μm.

Here, the present invention is not limited to the above-mentionedconstitutions and various modifications can be made without departingfrom the technical concept of the present invention.

In the liquid crystal display device having such a constitution, for onesubstrate on which the columnar spacers are formed, another substrate onwhich the columnar spacers are not formed is provided, and the columnarspacers include the columnar spacers which are brought into contact withanother substrate and the columnar spacers which are not brought intocontact with another substrate and hence, it is possible to largelyreduce the friction resistance against the displacement in plane ofanother substrate with respect to one substrate.

Accordingly, even when such a displacement is generated, anothersubstrate can easily return to the original position and hence, it ispossible to obviate a phenomenon that the displacement is maintained sothat the brightness irregularities occur.

Further, when an excessive pressure is exerted between another substrateand one substrate, the columnar spacers which have not been brought intocontact with another substrate so far are also brought into contact withanother substrate and hence, the columnar spacers can sufficientlywithstand the excessive pressure thus ensuring the gap between bothsubstrates.

Further, since the respective columnar spacers can be formed with theirheight set substantially equal, the increase of the manufacturing costof the liquid crystal display device can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an embodiment of the constitution ofpixels of a liquid crystal display device according to the presentinvention;

FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1;

FIG. 3 is a plan view showing another embodiment of the constitution ofthe pixels of the liquid crystal display device according to the presentinvention;

FIG. 4 is a cross-sectional view taken along a line IV-IV in FIG. 3; and

FIG. 5 is a plan view showing still another embodiment of theconstitution of the pixels of the liquid crystal display deviceaccording to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the liquid crystal display device of thepresent invention are explained hereinafter in conjunction withdrawings.

FIG. 1 is a constitutional view of an essential part of a display partshowing one embodiment of the liquid crystal display device according tothe present invention and also is a view which shows the constitution ofa liquid-crystal-side surface of one substrate out of a pair ofsubstrates which are arranged to face each other in an opposed mannerwith liquid crystal therebetween. Further, FIG. 2 is a cross-sectionalview taken along a line II-II in FIG. 1.

On the liquid-crystal-side surface of the first substrate SUB1, first ofall, the gate signal lines GL which extend in the x direction and arearranged in parallel in the y direction are formed.

These gate signal lines GL surround rectangular regions together withdrain signal lines DL described later and these regions constitute pixelregions.

Further, in a region defined between the respective gate signal linesGL, a counter voltage signal line CL which is arranged parallel to thegate signal line GL is formed. The counter voltage signal line CL isconnected with the counter electrode CT described later and a referencevoltage signal (which becomes the reference with respect to the videosignal) is applied to the counter electrode CT through the countervoltage signal line CL.

On a surface of the substrate SUB1 on which the gate signal lines GL andthe counter voltage signal lines CL are formed, an insulation film GImade of SiN, for example, is formed such that the insulation film GIalso covers the gate signal lines GL and the counter voltage signallines CL.

The insulation film GI has a function of an interlayer insulation filmwith respect to the gate signal lines GL and the counter voltage signallines CL in the regions where the drain signal lines DL described laterare formed, has a function of a gate insulation film in the regionswhere the thin film transistors TFT described later are formed, and hasa function of a dielectric film in the region where capacitive elementsCstg described later are formed.

Then, on a surface of the insulation film GI, semiconductor layers ASmade of amorphous Si, for example, are formed such that thesemiconductor layers AS are overlapped to portions of the gate signallines GL.

The semiconductor layers AS are semiconductor layers of the thin filmtransistors TFT, wherein by forming a drain electrode SD1 and a sourceelectrode SD2 on each semiconductor layer AS, it is possible toconstitute a MIS type transistor having the inversely staggeredstructure which uses a portion of the gate signal line as a gateelectrode.

Here, the drain electrodes SD1 and the source electrodes SD2 are formedsimultaneously with the formation of the drain signal lines DL.

That is, the drain signal lines DL which extend in the y direction inparallel and are arranged in the x direction are formed, portions of thedrain signal lines DL extend to upper surfaces of the semiconductorlayers AS thus forming the drain electrodes SD1 and, at the same time,the source electrodes SD2 are formed in a spaced-apart manner from thedrain electrodes SD1 by an amount of a channel length of the thin filmtransistors TFT.

The source electrode SD2 is formed such that the source electrode SD2extends into the inside of the pixel from the semiconductor layer ASsurface and traverses a center portion of the pixel in the y direction.The extension portion functions as the pixel electrode PX and generatesan electric field between the pixel electrode PX and the counterelectrode CT described later, and the optical transmissivity of theliquid crystal is controlled based on this electric field.

In forming the pixel electrode PX, the pixel electrode PX is overlappedto the counter voltage signal line CL by way of the insulation film GIand a capacitive element Cstg which adopts the insulation film GI as adielectric film is formed between the pixel electrode PX and the countervoltage signal line CL. The capacitive element Cstg has a function ofstoring the video signal supplied to the pixel electrode PX for arelatively long period and the like.

Here, in the above-mentioned explanation, the semiconductor layers ASare formed in the regions where the thin film transistors TFT areformed. In this embodiment, however, at the time of forming thesemiconductor layers AS, semiconductor layers ASI are alsosimultaneously formed on regions other than the regions where the thinfilm transistors TFT are formed and above the gate signal lines GL.

In this case, the semiconductor layer ASI is not formed for every pixelbut is formed at a rate of, for example, one with respect to a groupconsisting of a plurality of pixels which are arranged close to eachother. The semiconductor layers ASI have, as will become apparent fromthe explanation described later, a “bottom-up” function for setting aheight of an uppermost layer which is brought into contact with theliquid crystal greater at portions where the semiconductor layers ASIare formed than other portions. An advantageous effect obtained by thisconstitution will be explained later.

On the surface of the transparent substrate SUB1 on which the thin filmtransistors TFT, the drain signal lines DL, the drain electrodes SD1 andthe source electrodes SD2 are formed, a protective film PAS made of SiN,for example, is formed. The protective film PAS is a film which obviatesthe direct contact of the thin film transistors TFT with the liquidcrystal LC and prevents the deterioration of characteristics of the thinfilm transistors TFT.

Here, the above-mentioned protective film PAS may be constituted of, forexample, an organic material layer made of resin or a stacked body whichis constituted of an inorganic material layer and an organic materiallayer.

Further, the counter electrode CT is formed on an upper surface of theprotective film PAS. Provided that the counter electrode CT is formed atthe left and right sides with respect to the longitudinal direction ofthe pixel electrode PX basically, the counter electrode CT can performthe function thereof. In this embodiment, however, the counter electrodeCT is formed such that the counter electrode CT sufficiently covers thedrain signal line DL and the gate signal line GL. In other words, thereis provided a pattern in which openings are formed in a center portionof a conductive layer formed on the entire region of the display part (aregional part which is formed by a mass of the respective pixels) whileleaving peripheries of the respective pixel regions. This provision isprovided for terminating signal electric fields from the drain signallines DL and the gate signal lines GL to the counter electrode thuspreventing the signal electric fields from reaching the pixel electrodesPX.

A material of the counter electrode CT is made of a light transmittingconductive material such as, ITO (Indium Tin Oxide), ITZO (Indium TinZinc Oxide), IZO (Indium Zinc Oxide), SnO₂ (Tin oxide), In₂O₃ (IndiumOxide) or the like thus contributing to the enhancement of the numericalaperture of the pixels.

Further, on the upper surface of the transparent substrate SUB1 on whichthe counter electrode CT is formed, an orientation film AL is formedsuch that the orientation film AL also covers the counter electrode CT.The orientation film AL is a film which is directly brought into contactwith a liquid crystal LC and the direction of the initial orientation ofmolecules of the liquid crystal LC is determined based on rubbing formedon a surface of the orientation film AL.

FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1 andalso shows the substrate SUB2 which is arranged to face theabove-mentioned substrate SUB1 with the liquid crystal LC therebetween.

On the surface of the substrate SUB1, together with the counter voltagesignal lines CL, the insulation film GI, the protective film PAS and thelike, the semiconductor layers ASI which are formed separately from thesemiconductor layers AS for the thin film transistors TFT are provided.Due to the formation of these semiconductor layers ASI, surfaces of theportions of the semiconductor layers ASI which are brought into contactwith the liquid crystal LC are formed higher than other portions by anamount corresponding to a film thickness.

On the other hand, on a liquid-crystal-side surface of the substrateSUB2, a black matrix BM is formed such that the black matrix BM facesthe above-mentioned gate signal lines GL, for example. The black matrixBM is provided for enhancing a contrast of a display.

Here, the black matrix BM is formed such that the black matrix BM alsosufficiently covers the thin film transistors TFT on the substrate SUB1side, wherein by interrupting the radiation of an external light to thethin film transistors TFT, the black matrix BM can avoid the degradationof characteristics of the thin film transistors TFT.

On the surface of the substrate SUB2 on which the black matrix BM isformed, color filters CF are formed such that the color filters CF alsocover the openings of the black matrix BM. The color filters CF areconstituted of, for example, filters of respective colors consisting ofred (R), green (G), blue (B), wherein the filters having the same colorare formed in common in a group of respective pixel regions which arearranged in parallel in the y direction and the filters having colors inan arrangement of red (R), green (G), blue (B), red (R), are formed in agroup of pixel regions which are sequentially arranged close to eachother in the y direction.

On the surface of the substrate SUB2 on which the black matrix BM andthe color filters CF are formed in this manner, a leveling film OC isformed such that the leveling film OC also covers the black matrix BMand the color filters CF. The leveling film OC is constituted of a resinfilm which is formed by coating and is provided for eliminating astepped portion which becomes apparent due to the formation of the blackmatrix BM and the color filters CF.

Further, on an upper surface of the leveling film OC, to allow thesubstrate SUB2 to ensure a uniform gap (for example, 4 μm) with respectto the substrate SUB1, spacers SP are formed. The spacers SP are formedas columnar projection bodies (columnar spacers) which are formed byperforming the selective etching of a resin film, for example, of asubstantially uniform film thickness formed on the leveling film OC.Accordingly, the respective spacers SP which are formed in this mannercan be constituted as projection bodies having the substantially uniformheight.

In this embodiment, the spacers SP are formed at a rate of, for example,one for each pixel and these spacers SP are formed at positionscorresponding to the respective pixels. That is, with respect to thepixels in which the semiconductor layers ASI are formed among theabove-mentioned respective pixels, the spacers SP are arranged on theorientation film AL over the semiconductor layers ASI of the pixels suchthat top portions of the spacers SP face the semiconductor layers ASI inan opposed manner and, at the same time, other spacers SP which arearranged around these spacers SP are also formed on the correspondingpositions.

Accordingly, in a state that pressure of a given value or more is notapplied between the substrate SUB2 and the substrate SUB1, as shown inFIG. 1, with respect to the pixels provided with the semiconductorlayers ASI, the spacers SP provided to the pixels are brought intocontact with the substrate SUB1 side (to express more accurately,brought into contact with the orientation film AL), while other spacersSP around these spacers SP are in a state that other spacers SP are notbrought into contact with the substrate SUB1 side.

Here, as mentioned above, the above-mentioned semiconductor layers ASIare formed at a rate of, for example, one for a group consisting of aplurality of pixels which are arranged close to each other and thisimplies that one spacer SP is brought into contact with the substrateSUB1 with respect to the group of pixels. Accordingly, in the inside ofthe display part which is formed of the mass of the pixels, a largenumber of the spacers SP which are brought into contact with thesubstrate SUB1 side are arranged in a scattered manner and these spacersSP perform the function of maintaining the gap in a state that thepressure of the given value or more is not applied between the substrateSUB2 and substrate SUB1.

Here, the reason that the expression “state in which the pressure of thegiven value or more is not applied between the substrate SUB2 and thesubstrate SUB1” is used is that there exists a case in which anexcessive pressure is applied between the substrate SUB2 and thesubstrate SUB1 such as a case in which a user pushes the liquid crystaldisplay device with his finger. In this case, the spacers SP which arearranged to face the above-mentioned semiconductor layer ASI receive theelastic deformation and spacers SP other than these spacers SP arebrought into contact with the substrate SUB1 side. As a result, when theexcessive pressure is applied, all spacers in the region are added tomaintain the gap and hence, the pressure per one spacer is dispersed.Accordingly, it is possible to prevent the rupture of the spacers SP onthe semiconductor layers ASI.

In view of the above, when the excessive pressure is applied between thesubstrate SUB2 and the substrate SUB1, all spacers SP perform thefunction thereof, while when the excessive pressure is not appliedbetween the substrate SUB2 and the substrate SUB1, only some spacers SPout of the respective spacers perform the function thereof.

Accordingly, in the latter case, the friction resistance between thesubstrate SUB1 and the substrate SUB2 can be largely reduced and hence,even when the displacement of the substrate SUB2 is generated withrespect to the substrate SUB1 in the planner direction, a force whichreturns the substrate SUB2 still remains whereby it is possible toobviate a phenomenon that the displacement is not eliminated.

This may be also construed that two types of spacers, that is, thespacers for normal use and the spacers for emergency use are provided.

Further, two types of spacers SP which have different functions in thismanner can be constituted by forming the above-mentioned semiconductorlayers ASI at the time of forming the semiconductor layers AS of thethin film transistors TFT. Accordingly, there is no possibility that themanufacturing cost is increased.

Here, on a surface of the above-mentioned leveling film OC, in a statethat surfaces of the spacers SP are also included, the orientation filmAL is formed. The orientation film AL is a film which is directlybrought into contact with the liquid crystal LC and the direction of theinitial orientation of molecules of the liquid crystal LC is determinedbased on the rubbing formed on the surface thereof.

In the constitution shown in the drawing, the counter electrode CT isconstituted such that the counter electrode CT sufficiently covers atleast the gate signal lines GL and the drain signal lines DL. In thiscase, around surfaces of the substrate with which top portions of thecolumnar spacers SP are brought into contact, the counter electrode CThaving the large area is formed. Accordingly, the counter electrode CTfunctions as a hard pad with respect to the columnar spacers SP and, dueto the rigidity of the hard pad, the columnar spacers SP which arebrought into contact with these portions can be easily elasticallydeformed.

In view of the above, when the counter electrode CT having theabove-mentioned constitution is not formed, a hard pad having arelatively large rigidity such as a metal made hard pad may be formed.In this case, with respect to the surfaces of the substrate with whichthe top portions of the columnar spacers SP are brought into contact, itis preferable to form the hard pad on the surfaces or around thesesurfaces and, at the same time, to make the area of the hard pad greaterthan the area of top portions of the columnar spacers.

It is needless to say that, by only adopting the constitution in whichthe semiconductor layers ASI are arranged at positions which face thecolumnar spacers and the semiconductor layers ASI which are not arrangedon the positions, even when the displacement is generated between thesubstrate SUB1 and the substrate SUB2, the displacement can be easilyrestored and it is possible to obtain an advantageous effect to preventthe rupture of the spacers on the semiconductor layers ASI.

Further, in the illustrated constitution, although the constitution inwhich the pixel electrodes PX and the counter electrode CT is formed onthe same substrate SUB1 as an example of the liquid crystal displaydevice is adopted, even with the constitution in which the pixelelectrodes PX are formed on the substrate SUB1 and the counter electrodeCT is formed on the substrate SUB2, by adopting the constitution inwhich the semiconductor layers ASI are arranged at positions which facethe columnar spacers and the semiconductor layers which are not arrangedon the positions, even when the displacement is generated between thesubstrate SUB1 and the substrate SUB2, the displacement can be easilyrestored and it is possible to obtain an advantageous effect to preventthe rupture of the spacers.

Further, as mentioned previously, with respect to the columnar spacersSP which are formed on the substrate SUB2, there exist the columnarspacers SP which are brought into contact with the substrate SUB1 andthe columnar spacers SP which are not brought into contact with thesubstrate SUB1. In achieving such a constitution, it is desirable thatthe height of the substrate SUB1 which faces the columnar spacers SP isset such that the step difference or the difference in height betweensurfaces of portions with which the columnar spacers SP are brought intocontact and surfaces of portions with which the columnar spacers SP arenot brought into contact is within a range of 0.06 μm to 0.18 μm.

Here, the lower limit value 0.06 μm is determined in view of thecorrection which becomes necessary due to the difference in the thermalexpansion of the liquid crystal at a room temperature (for example, 25°C.) and a high temperature (for example, 40° C.). That is, this valuecan maintain the negative pressure in the inside of the display deviceeven when the sizes of the substrates SUB1, SUB2 are increased. On theother hand, the upper limit value 0.18 μm is a value necessary forgenerating a phenomenon that when the load is concentrated, the columnarspacers SP which are not brought into contact with the substrate SUB1 ina usual state are brought into contact with the substrate SUB1 todisperse the load before the columnar spacers SP which are brought intocontact with the substrate SUB1 in a usual state are ruptured underpressure.

Further, a diameter of the columnar spacers SP which are not broughtinto contact with the substrate SUB1 in a usual state may be set greaterthan a diameter of the columnar spacers SP which are brought intocontact with the substrate SUB1 in a usual state. In this case, it ispossible to enhance the restoring ability of the substrate SUB2 withrespect to the displacement of the substrate SUB2 with respect to thesubstrate SUB1 and, at the same time, it is possible to make thecolumnar spacers SP hardly broken even when the excessive load isapplied.

In any one of the above-mentioned embodiments, the spacers SP are formedon the substrate SUB2 side. However, by providing constitutional partswhich can replace the above-mentioned semiconductor layers ASI to thesubstrate SUB2 side, the spacers SP may be formed on the substrate SUB1side.

Further, in any one of the above-mentioned embodiments, the relativelyhigh portions are formed on the surface of the substrate SUB1 which isbrought into contact with the liquid crystal using the semiconductorlayers ASI. However, it is needless to say that it is possible to useother material layers which replace the semiconductor layers ASI andhave some thickness. FIG. 3 is a plan view showing such a constitution,wherein other material layers in place of the semiconductor layer ASIare indicated by a symbol DM. With the use of such material layers DM,it is possible to obtain an advantageous effect that the thickness canbe arbitrarily determined. In this case, it is needless to say that thematerial layers DM can be simultaneously formed when the material layersare formed on the surface of the substrate SUB1. As an example, thematerial layers DM may be simultaneously formed with the material layersof the drain signal lines DL.

As another example, the material layers DM may be formed by protectivefilm PAS or insulation film GI. In this case, protective film PAS orinsulation film GI make thicker at some portions out of area where faceto the spacer than other portions out of area where face to the spacer.Half-exposure method is suitable in this case as no additional photoprocess necessary.

Further, as shown in FIG. 5, the spacers SP which are arranged to facethe semiconductor layers ASI in an opposed manner and the spacers SPwhich are not arranged to face the semiconductor layers ASI in anopposed manner may be arranged at positions different from each other.This is because that the portions on which the semiconductor layers ASIare formed require some spaces around the portions.

The above-mentioned respective embodiments can be used in a single formor in combination. This is because it is possible to obtain theadvantageous effects of the respective embodiments in a single form orsynergistically.

The invention claimed is:
 1. A liquid crystal display device comprising:a first substrate and a second substrate with a liquid crystal layertherebetween; a plurality of spacers disposed on the first substrate;and a plurality of gate signal lines and a plurality of drain signallines, the gate signal lines and the drain signal lines being disposedon the second substrate, wherein the plurality of spacers include afirst spacer and a second spacer, wherein a projection portion isdisposed on the second substrate and counters the first spacer, whereinthe first spacer and the second spacer counter the plurality of gatesignal lines, wherein the projection portion includes a semiconductorlayer disposed on a corresponding one of the gate signal lines, and ametal layer stacked on the semiconductor layer.
 2. The liquid crystaldisplay device according to claim 1, wherein the first spacer and thesecond spacer are substantially equal in height.
 3. A liquid crystaldisplay device comprising: a first substrate and a second substrate witha liquid crystal layer therebetween; a plurality of gate signal linesand a plurality of drain signal lines, the gate signal lines and thedrain signal lines being disposed on the second substrate, a pluralityof pixel regions defined by the gate signal lines and the drain signallines, a plurality of spacers disposed on the first substrate, each ofthe plurality of spacers countering each of the gate signal lines, aprojection portion disposed on the second substrate, the projectionportion being arranged on one of the gate signal lines, and formed by atleast a semiconductor layer and a conductive layer, the conductive layerbeing disposed on the semiconductor layer, wherein the plurality ofspacers include a first spacer and a second spacer, a region where thefirst spacer is disposed corresponds to a region where the projectionportion is disposed in a plan view, and a region where the second spaceris disposed does not correspond to the region where the projectionportion is disposed in a plan view.
 4. The liquid crystal display deviceaccording to claim 3, wherein the plurality of spacers are columnarspacers.
 5. The liquid crystal display device according to claim 3,wherein the first spacer and the second spacer are substantially equalin height.
 6. The liquid crystal display device according to claim 3,wherein a plurality of the projection portion are disposed on the secondsubstrate, and a number of the plurality of the projection portion issmaller than a number of the plurality of spacers.
 7. The liquid crystaldisplay device according to claim 3, wherein the region where the firstspacer is disposed overlaps the region where the projection portion isdisposed in a plan view, and the region where the second spacer isdisposed does not overlap the region where the projection portion isdisposed in a plan view.